Marco Balato and Massimo Vitelli
The purpose of this paper is to discuss the main parameters influencing the performances of Distributed Maximum Power Point Tracking (DMPPT) and to present an algorithm aimed at…
Abstract
Purpose
The purpose of this paper is to discuss the main parameters influencing the performances of Distributed Maximum Power Point Tracking (DMPPT) and to present an algorithm aimed at the maximization of the energetic efficiency of the grid-connected PhotoVoltaic (PV) systems. Such an algorithm is based on the estimate of the optimal operating range of the input inverter voltage and of the optimal operating voltages of the PV modules.
Design/methodology/approach
The Fast Estimate of the Maximum Power Voltages algorithm, described in this paper, is based on the idea that the controllers of the DC/DC converters (DMPPT function) and the controller of the inverter (Central MPPT function) must be able to exchange useful data in order to carry out a suitable technique based on the jointed adoption of DMPPT and CMPPT function. Such a technique is essentially based on the knowledge, even if in approximate form, of the Power vs Voltage (P-V) characteristic of a string composed by PV modules and DC/DC converters and on the consequent fast identification of a set of operating points for the inverter and for the PV modules.
Findings
The main advantage of the proposed algorithm is represented by the fast identification of a set of operating points for the inverter and for the PV modules, which allows to obtain a marked increase of the speed of tracking both of the inverter and of the DC/DC converters performing the DMPPT function.
Originality/value
The simulation results, shown in this paper, confirm the validity of the proposed original approach.
Details
Keywords
Marcos Buestan, Cinthia C. Perez and Denise Rodríguez-Zurita
Health-care organisations face many challenges in delivering safe, high-quality services while experiencing significant pressure to increase productivity and reduce costs. In this…
Abstract
Purpose
Health-care organisations face many challenges in delivering safe, high-quality services while experiencing significant pressure to increase productivity and reduce costs. In this context, hospitals have implemented lean six sigma (LSS) programmes to improve their performance. This study aims to explore the application of LSS in three different non-profit Ecuadorian hospitals to comprehend the effectiveness of the methodology under this context.
Design/methodology/approach
A multiple-case analysis was performed in four phases: selecting the cases, defining a data collection protocol, performing a within-case analysis of each case and performing a cross-case analysis.
Findings
This research found that the LSS application positively impacts hospital performance indicators by reducing service time. The most frequently used tools include the supplier input process output customer diagram, value stream mapping, cause-and-effect diagram, five-why analysis, Gemba walk and paired two-sample test. Lastly, the results show that the most common challenges faced were lack of top management engagement, technical training and data availability.
Research limitations/implications
The study is limited by the constraint of a single Latin American country from which the cases were analysed. Collaboration with external partners, like universities, and government policies promoting training in continuous improvement methodologies are crucial for success. Academic implications stress the importance of integrating soft skills in LSS implementation and engineering education.
Originality/value
This study shows a multiple-case analysis of LSS in a Latin American country highlighting the most commonly used tools, their impact on performance and the challenges of implementing LSS in health-care organisations in non-profit Ecuadorian hospitals.